The president added "Tariffs are the greatest," and accused other countries of treating the U.S. like a " 'piggy bank' that's being robbed."

"Countries that have treated us unfairly on trade for years are all coming to Washington to negotiate," the president tweeted. "This should have taken place many years ago but, as the saying goes, better late than never!"

"Tariffs are the greatest! Either a country which has treated the United States unfairly on Trade negotiates a fair deal, or it gets hit with Tariffs. It’s as simple as that - and everybody’s talking! Remember, we are the 'piggy bank' that’s being robbed. All will be Great!"

Countries that have treated us unfairly on trade for years are all coming to Washington to negotiate. This should have taken place many years ago but,as the saying goes, better late than never!

Tariffs are the greatest! Either a country which has treated the United States unfairly on Trade negotiates a fair deal, or it gets hit with Tariffs. It’s as simple as that - and everybody’s talking! Remember, we are the “piggy bank” that’s being robbed. All will be Great!

The Trump administration has been engaged in a tense back and forth with China as each side has placed tariffs on the other nation's goods. Earlier this month, Trump announced a planned additional $200 billion in tariffs on Chinese goods and just last week the president said he is "ready to go" with levies on all Chinese imports.

“I’m not doing this for politics. I’m doing this to do the right thing for our country. We have been ripped off by China for a long time, and I told that to President Xi [Jinping],” Trump said.

Trump has also angered U.S. allies with tariffs on aluminum and steel ordered in May, citing national security concerns in order to place duties on imports from some top steel-producing allies including Canada, which issued a blistering statement on the measures.

"Let me be clear: These tariffs are totally unacceptable," Canadian Prime Minister Justin Trudeau said just before the measures were implemented. "Canada is a secure supplier of aluminum and steel to the U.S. defense industry, putting aluminum in American planes and steel in American tanks," Trudeau said. "That Canada could be considered a national security threat to the United States is inconceivable."

In recent weeks Canada has become one of several countries to announce retaliatory tariffs targeting U.S. exports, passing duties on approximately $13 billion worth of U.S. goods earlier this month.

Other countries against which the Trump administration has threatened or implemented trade action, have also vowed or passed reciprocal tariffs meant to harm U.S. exports in response to the president's actions.